Alternating current actuated controller



Jan. 15, 1935. J E BEGGS ALTERNATING CURRENT AGTUATED CONTROLLER FiledDec. 8, 1952 Inventor: James BBgggs,

big Aw His Attorney.

Patented Jan. 15, 1935 PATENT OFFICE ALTERNATING CURRENT ACTUATEDCONTROLLER James E. Beggs, Schenectady, N. Y., assignor to GeneralElectric Company, a corporation of New York Application December a,1932, Serial No. 646,284

6 Claims.

My invention relates to circuit controlling apparatus actuated byalternating current and particularly to such apparatus whose operationis light responsive. In certain prior forms of apv ,paratus of thischaracter in which the control "element, such as a photo-electricdevice, has been connected to the rest of the apparatus by relativelylong leads, diiliculties in obtaining satisfactory operation have beenencountered in some .cases due to the capacity effects of the longleads. One object of my invention is the provision of improved circuitcontrolling apparatus which will not be subject to the diflicultiesmentioned above. Another object is the provision of such apparatus whoseoperation will be independent of variations of the applied voltage.

A further object is the provision of such apparatus including a vaporelectric or are discharge device which will not be subject tochattering.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing, and its scope will bepointed out in the appended claims.

Referring to the drawing, Fig. 1 is a circuit diagram representing oneembodiment of my invention, and Fig. 2 represents a modificationthereof.

In Fig. 1 of the drawing a source of supply of alternating current,which for example may be a 60-cycle, 110-volt source, is shown at 1 and2 across which is connected the primary of the transformer 3. Thesecondary of this transformer is shown as comprising the windings 4, 5,

6, and 7, windings 4 and 7 being cathode heating windings. Winding 5 isconnected to supply energy to the grid controlled electron dischargeamplifier 8, such for example as a Pliotron tube.

The cathode of amplifier 8 is heated by a connection to winding 4 and inseries with the anode cathode circuit thereof are the resistors 9 and 10whose value may for example be 2,000 ohms and 10,000 ohms respectively.Connected across the resistor 10 is a capacitor 11 whose value forexample may be 1 mf. and also the photo-electric device 12, such as aphoto-electric tube, in series with the resistor 13 whose resistance forexample may be 10 megohms. The grid connection of amplifier 8 is made ata point between the photo-electric device 12 and the resistor 13.

With the above-described arrangement it will be seen that sinceresistors 9 and 10 are arranged in series with the anode cathode circuitof the amplifier 8, the photo-electric device will be supplied only withdirect or rectified current.

This is of particular advantage in cases where the photo-electric devicemust be arranged at some distance from the rest of the apparatus andhence would be connected therewith through relatively long leads. Sincedirect or rectified 5 current only is supplied to the photo-electricdevice I am able to avoid the troublesome capacity efiects due to thedistributed capacity of the long connecting leads. In order to indicatethat the leads connecting the photo-electric device 10 have distributedcapacity, I have represented a. capacitor by dotted lines connectedbetween the leads.

The amplifier 8 is shown as arranged to control the operation of thegrid controlled vapor electric or are discharge device 16. Theanodecathode circuit of device 16 is energized from winding 6 and inseries therewith is the relay 17 which is to be controlled by the lightfalling upon the photo-electric device 12. The cathode 20 of device 16is connected to be heated from the winding 7 and is also connected bythe lead 18 with the point 19 in the cathode circuit of amplifier 8. Thegrid of device 16 connects with the arm 21 of the potentiometer 22 whoseresistance for example may be 20,000 ohms. In this connection is theprotective resistance 23 which may be of the order of 1 megohm.

Assuming the photo device 12 to be brightly illuminated, the directcurrent supplied thereto through the amplifier 8 will hold the grid ofthe amplifier sufficiently positive with respect to its cathode that thedevice will pass a maximum current. Since the potential of the cathodeof device 16 is that of the point 19, the grid of 35 device 16 will atthis time be sufiiciently negative to prevent the passage of currentthrough device 16. Hence relay 1'7 will not be operated.

As the light reaching device 12 decreases the amplifier 8 passes lesscurrent and consequently 40 the negative bias of the grid of device 16becomes less until finally device 16 is tripped and begins passingcurrent. One of the advantages of applying a negative grid bias to thedevice 16 from the amplifier 8 as described above is that it 4eliminates any chattering or intermittent operation of device 16 whenthe light reaching the device 12 slowly diminishes.

The above described arrangement I have found gives excellent regulationsince it automatically compensates for variations in voltage of thesupply circuit. Thus with an increase in applied voltage the resultingresistance drop through resistors 9 and 10 causes an increase in thenegative grid bias of the amplifier 8. Con- 55 versely a reduction inapplied voltage results in a decrease in the negative grid bias of theamplifier 8. By suitable proportioning of the resistors 9, 10, and 13this circuit may even be caused to over-compensate Within limited rangesfor variations in applied voltage.

The modified form of my invention as represented by Fig. 2 is similar inall respects to that represented by Fig. 1 With the exception that therelative positions of the photo device and the resistor 13 areinterchanged. As arranged in Fig. 2 the device 16 will turn on or beginto pass current in response to an increase in light rather than adecrease in light as Fig. 1.

This modified form also is more stable than that shown in Fig. 1although it is somewhat less sensitive.

I have chosen the particular'embodiment described above as illustrativeof my invention and itwillbe apparent that various other modificationsmay be made without departing from the spirit and scope of my inventionwhich modifications I aim to cover by the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In combination, a photo-electric device, a rectifying electrondischarge device having a control element connected with said device, asource of supply of alternating current connected to energize saiddischarge device and means for energizing said photoelectric device withthe current rectified by said discharge device.

2. In combination, a photo-electric device, an electron discharge devicehaving anode and cathode elements and a grid connected with saidphoto-electric device, a source of alternating current supply connectedto energize said discharge device and means for energizing saidphotoelectric device with the current rectified by said dischargedevice.

3. In combination, a source of supply of a1- ternating current, a gridcontrolled rectifying electron discharge device and means for producinga resistance drop all connected together in a series circuit, aphotoelectric device connected to be energized by the rectified'voltageacross a portion of said means and a connection between said grid andsaid photoelectric device.

4.. In combination, a source of supply of alternating current, anelectron discharge device connected in circuit therewith having anode,cathode and grid elements, resistance means in said circuit arrangedbetween the cathode and the source including a photo-electric device anda connection between said grid and said resistance means whereby thelight received by said devicevaries the charge on said grid.

5. In combination, a source of supplyof alternating current, an electrondischarge devicehav ing anode, cathode and gridelements and resistancemeans all connectedtogether in a series circuit, said means beingarrangedbetween the cathode and the source and including a photoelectrictube and a connection between said grid i and an intermediate point ofsaid means.

6. In combination a rectifying-electron dis charge device having acontrol grid, means constructed and arranged to supply an alternatingcurrent to said device, a resistor connected in 1 series with saiddevice and said means, a photo-. electric device connected across saidf're'sistor whereby it is energized by rectified current and a connectionbetween said grid and said photoelectric device. I JAMES E. BEGGS.

